In the technical book "Hybrid Integration," published in 1986 by Dr. Alfred Huthig Verlag, Heidelberg, so-called Tape-Automated-Bonding (TAB) or film bonding is described in Section 8.3.3 on pages 219 ff. In this simultaneous bonding process, an integrated circuit is connected to a substrate by means of a flexible interconnect member. The flexible interconnect member is taken from a flexible circuit board, which is fabricated, for example, in the form of a conventional movie film and which consists of multiple layers of polyimide film. The flexible circuit board may be populated on one or both sides. The conductor paths necessary for connection are produced on the circuit board using known processes.
To make the connection arrangement, the integrated circuit is first placed inside an opening stamped out of the circuit board into which a portion of the conductor paths produced on the circuit board protrude freely. Then, the [protruding free ends of the] conductor paths are simultaneously connected to suitable connector elements of the integrated circuit.
This first bonding step, the so-called inner-lead-bond (ILB), is followed by a second bonding step, the connection of the interconnect member with the substrate which contains the circuitry in which the integrated circuit is to operate.
In this second bonding step, the so-called outer-lead-bond (OLB), the integrated circuit is stamped out of the flexible circuit board along with the surrounding part of the flexible circuit board which forms the flexible interconnect member, and the conductor paths of the interconnect member thus produced and provided for connection with the substrate are simultaneously soldered to the conductor paths of the substrate.
One advantage of the two-step bonding is, among other things, the possibility of subjecting the integrated circuits mounted on the flexible circuit board to various tests following the first bonding step and thus being able to eliminate defective specimens. The connections required for these tests can be produced on the flexible circuit board along with the conductor paths provided for the multiple connection arrangement. After the second bonding step, they are left behind on the part of the flexible [flexible] circuit board no longer needed.
Recently, there has been increasing discussion and development of integrated circuits which include optical functions in addition to electrical functions and which must be linked with optical waveguides for this purpose.
In the technical book "High Technology Multilayers" by H. Muller, published by Eugen G. Leuze Verlag, 7968 Saulgau, various connection techniques currently possible for optical waveguides are discussed in Chapter 5.7 (pp. 273 ff.). In addition to discretely installed fibers, optical strip waveguides produced using photolithographic techniques are discussed. From this reference, the connection of optical strip waveguides to integrated circuits would appear to be too expensive for extensive application because of the requirements for accuracy.